Stop SVNWrapper and GitWrapper from inheriting from scm.SVN and scm.GIT.

scm.py

 # Copyright (c) 2006-2009 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """SCM-specific utility classes."""
 
 import glob
 import os
 import re
 import shutil
@@ skipping 203 matching lines @@
     else:
       # Fall back on trying a git-svn upstream branch.
       if GIT.IsGitSvn(cwd):
         upstream_branch = GIT.GetSVNBranch(cwd)
     return remote, upstream_branch
 
   @staticmethod
   def GetUpstream(cwd):
     """Gets the current branch's upstream branch."""
     remote, upstream_branch = GIT.FetchUpstreamTuple(cwd)
-    if remote is not '.':
+    if remote != '.':
       upstream_branch = upstream_branch.replace('heads', 'remotes/' + remote)
     return upstream_branch
 
   @staticmethod
   def GenerateDiff(cwd, branch=None, branch_head='HEAD', full_move=False,
                    files=None):
     """Diffs against the upstream branch or optionally another branch.
 
     full_move means that move or copy operations should completely recreate the
     files, usually in the prospect to apply the patch for a try job."""
@@ skipping 136 matching lines @@
     # else, which is good.  Note that the patterns are only effective when
     # these commands are used in their ordinary forms, the patterns are invalid
     # for "svn status --show-updates", for example.
     pattern = {
           'checkout': update_pattern,
           'status':   status_pattern,
           'update':   update_pattern,
         }[args[0]]
     compiled_pattern = re.compile(pattern)
     # Place an upper limit.
-    for i in range(1, 10):
+    for _ in range(1, 10):
       previous_list_len = len(file_list)
       failure = []
 
       def CaptureMatchingLines(line):
         match = compiled_pattern.search(line)
         if match:
           file_list.append(match.group(1))
         if line.startswith('svn: '):
           failure.append(line)
 
       try:
         SVN.RunAndFilterOutput(args,
                                in_directory,
                                options.verbose,
                                True,
                                CaptureMatchingLines)
       except gclient_utils.Error:
         # We enforce that some progress has been made or HTTP 502.
-        if ([True for f in failure if '502 Bad Gateway' in f] or
+        if (filter(lambda x: '502 Bad Gateway' in x, failure) or
             (len(failure) and len(file_list) > previous_list_len)):
           if args[0] == 'checkout':
             # An aborted checkout is now an update.
             args = ['update'] + args[1:]
           continue
         # No progress was made or an unknown error we aren't sure, bail out.
         raise
       break
 
   @staticmethod
@@ skipping 334 matching lines @@
     if not cur_dir_repo_root:
       return None
 
     while True:
       parent = os.path.dirname(directory)
       if (SVN.CaptureInfo(parent, print_error=False).get(
               "Repository Root") != cur_dir_repo_root):
         break
       directory = parent
     return GetCasedPath(directory)